A critical but understudied area of research is why people stop using drugs, especially African American adults. This question is the primary focus of the proposed study. African Americans have the same or less substance use as adolescents compared to Whites, but as they age into adulthood they are less likely to desist use and more likely to develop use disorders. Moreover, drug use significantly impacts health, with adult drug use problems being more evident in older African Americans than in Whites, such as higher drug-related mortality and morbidity. We address this important public health issue using data spanning more than 35 years from a comprehensive developmental epidemiological study of a community cohort of urban African Americans first studied at age six (N=1242), then in adolescence, and at ages 32 and 42. This inner city Chicago cohort represents a 1960 birth cohort, considered to have the highest rates of adolescent drug use. Information from mothers, teachers, and official school, criminal, and death records are integrated with data from cohort members to build a study that provides an invaluable opportunity to examine the impact of life events on patterns of substance use over the life course. Specific aims are to: 1) examine the impact of individual life events on long-term patterns of drug use; 2) identify conditions under which life events impact long-term drug use patterns, and 3) determine what individual-level or contextual factors moderate the impact of life events on long-term patterns of drug use. The proposed project draws primarily on the age-graded theory of informal social control from criminological literature and applies it to substance use, extending our understanding of the relationship between life events and desistance from deviance (Sampson & Laub, 1993; Laub & Sampson, 2003). Few life events beyond marriage, work, and military service have been studied in this regard. Thus, we seek to study a wider array of life events that can alter substance use, and investigate conditions under which life events impact substance use patterns. Yet, not everyone who experiences a life event will alter their drug use trajectory, as evidenced by the finding of variability in the impact of life events in the stress literature basedon accumulation of events and moderating factors (see Thoits, 2010). In this project, we investigate quality of the life event and additional conditions under which life events impact substance use desistance such as quantity, combinations, timing, and ordering of life events. We also investigate moderating effects from stable individual differences (e.g., social adaptation) and adult influences (e.g., history of depression). The proposed project uses longitudinal methodologies (e.g., hierarchical linear modeling) and adopts a person-oriented approach, considering the individual as a whole to better understand stability and change in substance use. This work will extend our understanding of the role of informal social control stemming from individual life events as potential turning points in substance use. Findings will inform intervention development by identifying pivotal influences in adulthood that facilitate desistance from substance use.